CARSON, Calif. – The LA Galaxy weren't pleased with their effort in Sunday night's loss to Houston, nor with their inability to create better chances against an organized Dynamo defense, nor with Landon Donovan's failure to convert from the penalty spot.

PENALTY: Hall slides out on Villarreal

And they were particularly displeased with referee Allen Chapman's decision not to send off Dynamo goalkeeper Tally Hall following his foul on Jose Villarreal that set up the 25th-minute spot kick that Donovan missed.

All of it was game-changing, certainly. Hall's expulsion would have left Houston with 10 men for 65 minutes and forced Dynamo head coach Dominic Kinnear to make a change, and Donovan would have provided a lead had he hit the net.

“The referee certainly screwed that play up big-time, but I'll let [the league] deal with that,” Galaxy coach Bruce Arena said. “I think in most cases, that's a red card as well. Not to even get a card – if he gives a yellow card, you can understand that maybe, but remarkably, he didn't give a card on the play.”

It occurred in the 24th minute. Donovan sent Villarreal into the open with a through ball, and the second-year forward tried to cut right into space when Hall confronted him at the top of the box. There was contact, and Villarreal went sprawling. Chapman immediately awarded the penalty, but he kept his cards in his pocket.

WATCH: Postgame reaction from Bruce Arena

“I think we all would have argued [with Chapman] if we'd known it was an issue,” Magee said. “I've never seen a guy come out and clean somebody out on a breakaway [and not be shown the red card]. “You almost always get a red card, and then he doesn't give him a yellow. ... He comes flying out and clobbers him. It wasn't one of those where he nicks his heel; he comes out and clobbers him.

“We're not making excuses. The ref missed a handful of calls, the linesmen were watching a different game, but having said that, that's not why we lost the game. We lost the game because we didn't show up. But the refs didn't show up either.”

Fourth official Ricardo Salazar said, in answer to a written question, that Chapman didn't eject Hall because Villarreal's touch took the ball in the “direction of the corner or touchline.” It “was not going toward goal.” And there was no caution, Salazar said, because Chapman “deemed” the challenge to not be “reckless or tactical in nature.”

“If it's not a red card, then you don't give a red card in either case,” Donovan said. “If it is a red card, then you give a red card in both cases.

"I think we just want consistency from officials, because now we see two today where nobody really knows what the outcome is going to be. If you blatantly take down a forward as he's going to goal, I think it's probably a red card. He probably got that one wrong.”